Sunday, 17 November 2013

Microbes can help solve murder mysteries

Studies on decomposing mice suggest that the microbial
content of a corpse can offer clues as to how old a body is and the
approximate time that death occurred.

From studies on dead and decaying mice, where the microorganisms were examined, researchers have been able to narrow
down the times of death of mice to three-day windows. This is by
identifying the microbes present in and on their bodies using DNA
sequencing. This came from studies on 40 decomposing mice over 48 days.

Commenting on the study, Jessica Metcalf, a postdoc at the University of
Colorado Boulder and an author of the study, told NPR’s All Things
Considered that: "What we’re looking for is whether the microbial
community changes in a clock-like manner." The answer was 'yes it does'.

To show this, researchers collected samples of archaea, microbial eukaryotes, and bacteria from their skin, from within their abdominal cavities, and from soils associated with each corpse. They found that the bacteria, particularly those from the order Rhizobiales, were especially useful for estimating time of death.

The team is now working to estimate time of death in humans using a
similar approach. Currently researchers estimate time of death by
looking at the development of blow fly larvae in corpses. The new
research suggests that the microorganisms could present an equivalent
method or even something more accurate.

The findings have been published in the journal eLife.
The free-to-read paper is titled "A microbial clock provides an
accurate estimate of the postmortem interval in a mouse model system."